Portable electronic apparatus having an electro-magnetic shield supporting a keyboard

ABSTRACT

A portable computer includes a housing and a display unit. The display unit is attached to the housing to be movable between a closed position and an opened position. The portable unit may also include a keyboard which can be covered by the display when the display is in the closed position. A circuit board is proximate to the bottom wall of the housing. A shield plate for magnetically shielding the circuit board is disposed inside the housing proximate to the circuit board and can be between the circuit board and the keyboard if a keyboard is provided. At least one supporting member extends from the bottom face of the shielding plate and abuts the circuit board to prevent the keyboard unit, if one is provided, from bending toward the circuit board. The shield plate may include an edge which is supported on the housing. The portable computer may also include bosses positioned between the bottom wall of the housing and the circuit board.

This is a continuation of application Ser. No. 07/935,252, filed on Aug.27, 1992, which was abandoned upon filling hereof which in turn, is adivisional of application Ser. No. 07/695,501, filed May 6, 1991, nowU.S. Pat. No. 5,255,154.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Background of the Invention

The present invention relates to portable electronic apparatuses such aslaptop computers, word processors, etc.

2. Description of the Related Art

Portable computers, called laptop computers, have recently beenspreading for general use. The computers of this type comprises ahousing and a display unit rockably mounted thereon. The display unit isput on the housing when not in use, and is rocked to an operatingposition when it is to be operated.

Conventionally, a portable computer has a software-based function toprevent wrong operation. Although this preventive function provides acertain measure of effect, it may possibly be nullified when thecomputer itself is ready for operation.

Since a large number of heating components are arranged in the computerhousing, the computer is generally provided with a cooling mechanism.This cooling mechanism includes, for example, a cooling fan arranged inthe housing. After the components are cooled by means of the outsideair, which is introduced into the housing through intake ports in thehousing by means of the fan, the air is discharged through exhaust portsformed in the housing.

In consideration of its portability, however, the portable computer ismade as light in weight and compact as possible. It is difficult,therefore, to secure wide enough opening areas for the intake andexhaust ports in the housing, so that sufficient cooling air cannot beeasily introduced into the housing. Further, the cooling fan producesrelatively great operating sounds, which result in undesired noises.

Since the housing of the portable computer is compact, as describedabove, a large number of components must be efficiently arranged in thehousing.

The portable computer is provided with a substantially rectangularkeyboard unit, which is mounted on the housing so that its peripheraledge portion is supported thereby. If keys of the keyboard unit,especially the ones situated in the central portion of the keyboardunit, are deeply depressed, therefore, the central portion of thekeyboard unit sometimes may bend in the direction of the depression. Insuch a case, the keyboard unit interferes with underlying electronicparts, thereby possibly damaging them.

Some conventional portable computers are provided with an expansion unitwhich can contain an expansion component for expanding the function ofthe computer. This expansion unit is removably mounted on the housing.In attaching the expansion unit to the housing, a unit-side connector isconnected to a housing-side connector. In order to connect these twoconnectors with accuracy, they must be accurately positioned withrespect to each other. Accordingly, the expansion unit and the housingshould be manufactured with high accuracy, thus entailing increasedcosts.

SUMMARY OF THE INVENTION

The present invention has been contrived in consideration of thesecircumstances, and its object is to provide a portable electronicapparatus capable of securely preventing wrong use.

Another object of the invention is to provide a portable electronicapparatus whose heating components can be efficiently cooled.

Still another object of the invention is to provide a portableelectronic apparatus in which parts can be set efficiently utilizing theinside space of a housing.

A further object of the invention is to provide a portable electronicapparatus in which a keyboard unit can be prevented from bending lestparts be damaged thereby.

A still further object of the invention is to provide an electronicapparatus in which an expansion unit can be securely connected to theelectronic apparatus with use of a simple structure.

In order to achieve the above objects, an electronic apparatus accordingto an aspect of the present invention is designed so that its wrong usecan be mechanically prevented. More specifically, the electronicapparatus comprises a housing, input means mounted on the housing, and adisplay unit arranged on the housing and rotatable between a closedposition in which the input means is covered by the display unit and adesired rotated position in which the input means is exposed. Thedisplay unit includes latch means which engages the housing to keep theunit in the closed position when the unit is rotated to the closedposition. The latch means includes a latch hook, movable between a latchposition and a release position, and an interlocking member movable ininterlock with the latch hook, The display unit is provided with keymeans for restraining the movement of the interlocking member.

If the key means is turned on with the display unit in the closedposition, according to the arrangement described above, the display unitcannot be lifted from the housing, so that the electronic apparatusitself is disabled from operating.

An electronic apparatus according to another aspect of the presentinvention comprises a circuit board mounted with a heating component, ahousing containing the circuit board and the heating component andhaving a wall portion inclined with respect to the circuit board, andcooling means provided at the housing, for cooling the inside of thehousing. The cooling means includes a cooling fan arranged in thehousing, and intake ports formed in the wall portion.

Since the wall portion is inclined in this manner, according to thisarrangement, intake ports with a wider opening area can be formed in thewall portion than in the case where intake ports are formed in a wallportion of the same height which extends perpendicular to the circuitboard. Even though the wall portion is lowered in profile so that thehousing is compact, therefore, intake ports with a wide opening area canbe formed and sufficient cooling air can be guided into the housingthrough the ports.

According to the present invention, moreover, a housing of theelectronic apparatus includes a wall portion which, facing the exhaustside of a cooling fan, has a plurality of exhaust ports through whichthe air from the fan is discharged from the housing. Guide ribs with astreamlined cross section, which extend along the respective end edgesof the exhaust ports, are formed at least on those parts of the wallportion which face the fan.

With use of these guide ribs, in this arrangement, the air dischargedfrom the cooling fan can be smoothly guided into the exhaust ports andsmoothly discharged from the housing. Thus, the cooling efficiencyinside the housing can be improved.

According to the electronic apparatus of the present invention,furthermore, cooling means for cooling the inside of a housing of theapparatus includes a cooling duct, having an intake portion and anexhaust portion and arranged in the housing, heating components beinglocated in the cooling duct, and a cooling fan opposed to the exhaustportion of the cooling duct, for sucking air from the intake portionthrough the duct. Spacing means is arranged between the cooling fan andthe exhaust portion to keep the fan at a predetermined distance from theexhaust portion.

In this arrangement, the cooling fan is kept at the predetermineddistance from the exhaust portion of the cooling duct by means of thespacing means, so that eddies in the exhaust portion of the duct can bereduced. Thus, the intake efficiency of the cooling means can beimproved, and the noise level of the fan can be lowered.

An electronic apparatus according to still another aspect of the presentinvention comprises a housing having a bottom wall, and a keyboard unitremovably mounted on the housing and inclined to the bottom wall. Thekeyboard unit is connected electrically to a circuit board in thehousing by means of a connecting cable. One end of the cable is fixed tocircuit substrate, and the other end is removably connected to aconnector which is attached to the keyboard unit. The connector issituated within a region in which the distance between the keyboard unitand the bottom wall of the housing is greatest.

According to the electronic apparatus constructed in this manner, theconnector for the connecting cable is situated within the region inwhich the distance between the inclined keyboard unit and the bottomwall of the housing is greatest, so that this region, which is liable tobe a dead space, can be effectively utilized. Also, there is no need ofsecuring a space for the connector over the circuit board in thehousing. Thus, the housing can be made more compact.

An electronic apparatus according to a further aspect of the presentinvention comprises a housing having a bottom wall carrying a circuitboard thereon, and a substantially rectangular keyboard unit mounted onthe housing and facing the circuit board. The peripheral edge portion ofthe keyboard unit is supported on the housing, and support postsprotrude from the central portion of the unit toward the circuit board.The respective extended ends of the posts rest on the circuit board.

According to the electronic apparatus constructed in this manner, evenif keys situated in the central portion of the keyboard unit are deeplydepressed, the keyboard unit can be prevented from bending by the agencyof the support posts. Thus, parts under the keyboard unit can beprevented from being damaged.

An electronic apparatus according an additional aspect of the presentinvention comprises a housing having a storing section opening to theouter surface thereof, a circuit board arranged in the housing, a firstconnector fixed to the circuit board and exposed to the inside of thestoring section, and an expansion unit removably fitted to the storingsection so as to constitute part of the outer surface of the housing.The expansion unit includes means for expanding the function of theelectronic apparatus, a second connector connected to the firstconnector, and a supporting member for supporting the second connector.The supporting member is provided on the expansion unit so as to bemovable in a direction substantially perpendicular to the connectingdirection of the first and second connectors.

According to the electronic apparatus constructed in this manner, if thesecond connector is slightly displaced with respect to the firstconnector when the expansion unit is fitted in the storing section ofthe housing, the second connector can be accurately positioned withrespect to the first connector by moving the supporting member, so thatthe second connector can be securely connected to the first connector.Since the two connectors can be securely connected to each other withuse of such a simple structure, the expansion unit and the housing neednot be manufactured with very high accuracy. An electronic apparatusaccording to still another aspect of the present invention comprises ahousing having a bottom wall, and a circuit board proximate to thebottom wall. A shielding plate, disposed proximate to the circuit board,has an edge portion supported on the housing. The shielding platemagnetically shields the circuit board. The electronic apparatus alsoincludes at least a spacing means for maintaining spacing between theshielding plate and the circuit board. There is also at least one bossdisposed between the bottom wall and the circuit board. The electronicapparatus may also contain cushioning members disposed between thecircuit board and the supporting member. Finally, the supportingmembers, the bosses and the cushioning members may be arranged in a linesubstantially perpendicular to the bottom wall. According to theelectronic apparatus construed in this manner, the circuit board can beshielded from damage.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate a presently preferred embodimentof the invention, and together with the general description given aboveand the detailed description of the preferred embodiment given below,serve to explain the principles of the invention.

FIGS. 1 to 15 show a portable computer according to an embodiment of thepresent invention, in which

FIG. 1 is a perspective view of the computer with its display unit open,

FIG. 2 is a perspective view of the computer with its display unitclosed,

FIG. 3 is a sectional view of the computer,

FIG. 4 is an exploded perspective view showing the front portion of thecomputer,

FIG. 5 is a perspective view of the computer with its top cover off,

FIG. 6 is cutaway side view showing a cooling fan and exhaust ports,

FIG. 7 is an enlarged perspective view showing the exhaust ports andmembers associated therewith,

FIG. 8 is a bottom view of the computer, showing a storing section foran expansion box,

FIG. 9 is a perspective view showing the expansion box,

FIG. 10 is a perspective view showing a latch mechanism,

FIG. 11 is an exploded perspective view of a latch hook,

FIG. 12 is a perspective view of the latch hook,

FIG. 13 is a schematic sectional view of the front portion of thecomputer, showing a state in which a latch hook is in engagement with alatch hole,

FIG. 14 is a schematic sectional view of the front portion of thecomputer, showing a state in which the latch hook is disengaged, and

FIG. 15 is a sectional view corresponding to FIG. 13, showing thepositional relationship between a dial key and the latch mechanism; and

FIG. 16 is a side view, partially in section, showing a computeraccording to a modification of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A portable computer according to an embodiment of the present inventionwill now be described with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the computer 1 comprises a base unit 3, foruse as a housing, and a display unit 5. A substantially rectangularkeyboard unit 7 is mounted on the upper surface of the front portion ofthe unit 3. An expansion box 9 is attached to the bottom portion of therear portion of the unit 3. A handle 17 is slidably attached to thefront end of the base unit 3. An operator can hold the handle 17 as heor she carries the computer 1. The handle 17 has a grip section 59 and apair of leg sections 61 slidably mounted on the base unit 3.

The base unit 3 includes a substantially rectangular bottom case 11 anda rear top cover 13 concealing the rear portion of the case 11. A topwall of the cover 13 is stepped so that its front side is recessed, anda recess 27, opening upward and forward, is formed in the center of thestepped portion. A socket 15, which is arranged in the recess 27, isrockably mounted on the top cover 13. A cable guide duct 19 is rockablyfitted in the lower part of the socket 15. The duct 19 serves to guidecables which are led out from the base unit 3 into the display unit 5.The guide duct 19 is fixed in the recess 27 of the top cover 13. Thedetailed structure of the guide duct 19 is disclosed in U.S. Pat. No.4,864,523.

A leg section 37 of the display unit 5 is fitted in and screwed to thesocket 15. A decorative cover 25 is attached to the upper portion of thefront face of the socket 15. The cover 25 conceals tapped holes whichare used to fix the socket 15 and the display unit 5. The constructionof the cover 25 are described in detail in U.S. patent application Ser.No. 07/598,519 filed Oct. 17, 1990. The display unit 5 can be disengagedfrom the socket 15 by taking off the cover 25 and then removing screwswhich are used to fix the socket 15 and the unit 5. The construction ofa hinge mechanism for the display unit 5 are described in detail in U.S.patent application Ser. No. 07/428,772 filed Oct. 30, 1989, now U.S.Pat. No. 5,144,290.The display unit 5 and the base unit 3 are groundedthrough the socket 15. The construction of a grounding mechanism forthis purpose are described in detail in U.S. patent application Ser. No.07/576,650 filed Sept. 5, 1990, now U.S. Pat. No. 5,138,565.

A number of intake ports 21 for introducing cooling air into the baseunit 3 are bored in the rear portion of the right-side wall of the topcover 13, and a number of exhaust ports 23 (see FIG. 7) are bored in therear portion of the left-side wall of the top cover 13. A plurality ofLED lamps 29 are arranged each extending from the upper edge of thestepped portion of the cover 13, on one side thereof, to the uppersurface. The lamps 29 serve to inform the operator of the operatingstate of the portable computer 1. A burglarproof hook (not shown) forthe computer 1 is provided on the left side face of the base unit shownin FIG. 1 This burglarproof hook is described in detail in PublishedUnexamined Japanese Utility Model Application No. 2-65384.

The display unit 5 includes a liquid crystal display (LCD) 31, a baseframe 33 for fixedly holding the LCD 31, and a display cover 35 forconcealing all the area of the LCD 31 except the display screen thereof.The leg section 37, which is removably fitted in the socket 15, isformed integrally with the base frame 33. The display unit 5 isrotatable integrally with the socket 15 between a rotated position inwhich it is inclined at a desired angle to the base unit 3, as shown inFIG. 1, and a closed position in which it conceals the keyboard unit 7,as shown in FIG. 2. A pair of latch hooks 39 are provided individuallyat the opposite ends of the upper portion of the base frame 33. A largenumber of intake slits 41 are formed at the bottom end of the displaycover 35. Cooling air is introduced into the display unit 5 through theslits 41. In the display unit 5, converters (not shown) are providedindividually on the opposite side faces of the LCD 31. The convertersare used to boost a low voltage fetched from the base unit 3 through thesocket 15 to a high voltage. A mounting structure for the converters isdescribed in detail in U.S. patent application Ser. No. 07/577,535 filedSept. 5, 1990.

The keyboard unit 7 includes a keyboard body 43 and a keyboard frame 45which holds the body 43 so as to conceal the body except keys. A pair oflatch holes 47 are formed at the front portion of the upper surface ofthe keyboard frame 45. The latch hooks 39 of the display unit 5 areadapted to engage the holes 47, individually. Hole covers 49 arerockably mounted on the inner surface of the frame 45. They are adaptedto close their corresponding latch holes 47 when the hooks 39 aredisengaged from the holes 47.

A dial key 55 is provided substantially in the center of the top edge ofthe display unit 5. It serves to restrict the movement of the latchhooks 39, thereby locking the display unit 5 in the closed positionshown in FIG. 2. A large number of exhaust slits 57 are formed coveringboth side faces and rear face of the base frame 33 of the display unit5. Air can be discharged from the unit 5 through the slits 57 so thatthe inside of the unit 5 is cooled.

A floppy disk drive (FDD), an expansion board, a modem card, etc. arecontained in the expansion box 9. The box 9 is attached to the bottomcase 11 of the base unit 3 by means of screws. A loading slot 53 for afloppy disk is formed in that side wall of the expansion box 9 whichconstitutes part of a side wall of the base unit 3.

FIGS. 3 and 4 are views for illustrating the arrangement of parts in thebase unit 3.

A main printed circuit board (PCB) 63 is mounted on the bottom surfaceof the bottom case 11 of the base unit 3 so as to face the keyboard unit7. The bottom surface of the case 11 constitutes a bearing surface 65 ofthe present invention. A plurality of bosses 67 are formed on thebearing surface 65, and the main PCB 63 is mounted on the bosses 67. ThePCB 63 is mounted with a large number of electronic parts, includingSOJ-type memory elements 69 surface-mounted on the PCB 63, pin-mountedZIP-type memory elements 71, and DIP-type memory elements 86. Theelectronic parts further include inclined SIMM sockets 73, upright SIMMsockets 75, a first connector 77 to which a connector in the expansionbox 9 is connected, and SIMMs 79 and 72 fitted to the sockets 73 and 75.A plurality of circular shock-absorbing rubbers 81, e.g., three innumber, are fixed to the central portion of the upper surface of the PCB63. Each rubber 81 is situated just over its corresponding boss 67 ofthe bottom case 11.

A shielding plate 83 for magnetically shielding the main PCB 63 ismounted on the front portion of the bottom case 11 and situated betweenthe keyboard unit 7 and the PCB 63, thereby covering the PCB 63.Columnar support posts 85 are screwed to the shielding plate 83,extending therefrom toward the PCB 63. These posts 85 are situatedcorresponding individually to the rubbers 81 on the main PCB 63 so thattheir respective lower ends rest on their corresponding rubbers.

The body 43 of the keyboard unit 7 has a rectangular substrate or acircuit board 87 which carries a large number of keys thereon. Thecircuit board 87 is situated adjacent and parallel to the shieldingplate 83. The keyboard frame 45 is fitted to the upper end edge of thefront portion of the base unit 3. Shock-absorbing rubbers 89 are pastedindividually on those portions of the lower surface of the keyboardsubstrate 87 which are situated right over the support posts 85.

Thus, the shielding plate 83, which is situated under the keyboard unit7, has the support posts 85 which project toward the PCB 63 and whoserespective lower ends rest individually on the rubbers 81 on the PCB.Even if the keys in the central portion of the keyboard unit 7 aredeeply depressed, therefore, the central portion of the plate 83, alongwith the keyboard substrate 87, can be prevented from bending toward thePCB 63. Thus, the shielding plate 83 can be prevented from damaging theelectronic parts on the PCB 63 by running against them. By the use ofthe shock-absorbing rubbers 81 and 89 on the bottom and top of the eachsupport post 85, the impact of the deflection of the keyboard on themain PCB 63 can be reduced.

The keyboard unit 7 is connected electrically to a circuit board 90 onthe side of the base unit 3 by means of a flat cable 91. A connector 93is fixed to the rear end of the lower surface of the keyboard substrate87 on the side of the top cover 13. One end of the cable 91 is removablyconnected to the connector 93. The other end of the cable 91 is soldereddirectly to the circuit board 90. The board 90 is fixed in the bottomcase 11, and is situated below the rear top cover 13.

The flat cable 91 can be disconnected from the keyboard unit 7 at thelocation of the connector 93 which fixed to the lower surface of thekeyboard substrate 87, as described above. In removing the unit 7 fromthe base unit 3, therefore, the top cover 13 need not be removed fromthe bottom case 11, so that the efficiency of operation for assemblingor disassembling the apparatus is improved.

As shown in FIG. 16, the other end of the flat cable 91 may be solderedto the main PCB 63 which is situated under the keyboard unit 7. In thiscase, just as in the aforesaid case, the flat cable 91 can bedisconnected from the keyboard unit 7 at the location of the connector93. In removing the unit 7 from the base unit 3, therefore, the topcover 13 and the shielding plate 83 need not be removed from the bottomcase 11, so that the efficiency of operation for assembling ordisassembling the apparatus is improved.

In FIGS. 3 and 16, reference numeral 95 denotes a reinforcing plate 95for reinforcing the base unit 3, which is located substantially in thecentral portion of the bottom case 11.

The keyboard unit 7 of the present embodiment is declined forward ortoward the operator to facilitate the operator's keyboard operation, asshown in FIGS. 3 and 4. Therefore, the keyboard substrate 87 and theshielding plate 83 are declined in like manner. The plate 83 constitutesa slanting surface of the present invention.

In the base unit 3 constructed in this manner, the distance between theshielding plate 83 and the PCB 63 is greatest in the vicinity of thecenter of the unit 3, and decreases toward the front end of the unit 3.In order to mount the electronic parts in the base unit 3 with highefficiency and with high density, therefore, the upright SIMM sockets 75are arranged in a first region 74 of the main PCB 63 where the distancebetween the PCB 63 and the shielding plate 83 is greatest. These sockets75, which are arranged adjacent and parallel to one another, extend inthe transverse direction of the base unit 3. The SIMMs 72 are removablyfitted to the sockets 75 and extend substantially at right angles to thePCB 63. Each SIMM 72 has an elongated rectangular substrate and aplurality of memory elements arranged on the substrate in thelongitudinal direction thereof. The inclined SIMM sockets 73 arearranged in a second region 76 of the main PCB 63 which is situated onthe front end side of the base unit 3 with respect to the first region74, and in which the distance between the PCB 63 and the shielding plate83 is shorter than in the first region. These sockets 73, which arearranged adjacent and parallel to one another, extend in the transversedirection of the base unit 3. The SIMMs 79 similar to the SIMMs 72 areremovably fitted to the sockets 73 and inclined at a predetermined angleto the main PCB 63 in the same direction as the shielding plate 83. Inthe present embodiment, the SIMMs 79 are inclined at an angle greaterthan the angle of inclination of the shielding plate 83, with respect tothe PCB 63. However, this angle of inclination of the SIMMs 79 may besuitably set depending on the required mounting density.

The SIMMs 72 and 79, which have the same size and shape with oneanother, are attached to their corresponding sockets 75 and 73 in amanner such that the longer sides of their respective substrates extendparallel to the PCB 63 and the shielding plate 83.

In the first region 74 of the main PCB 63, as described above, the SIMMs72 are mounted upright, so that the mounting density of the parts isvery high. In the second region 76 where the SIMMs 79 cannot be mountedupright, on the other hand, the SIMMs 79 are inclined in the samedirection as the shielding plate 83. Although the mounting density inthis region is lower than that in the first region, therefore, the partscan be mounted with the highest possible mounting density inconsideration of the distance between the PCB 63 and the plate 83.

The ZIP-type memory elements 71, the DIP-type memory elements 86, etc.are mounted in a third region 78 of the main PCB 63 which is situated onthe front end side of the base unit 3 with respect to the second region76, and in which the distance between the PCB 63 and the shielding plate83 is shorter than in the second region. Further, the SOJ-type memoryelements and other low-profile elements are mounted in a fourth region80 of the main PCB 63 in which the distance between the PCB 63 and theshielding plate 83 is shorter than in the third region 78.

According to the portable computer constructed in this manner, the partsare disposed in the individual regions of the main PCB 63, and theupright SIMM sockets 75 and the inclined SIMM sockets 73 are properlyused, depending on the distance between the PCB 63 and the shieldingplate 83. Although the distance between the PCB 63 and the shieldingplate 83 decreases from the central portion of the base unit 3 towardthe front end portion thereof, therefore, the parts can be arrangedwithout substantially lowering the mounting density.

As mentioned before, the connector 93 for electrically connecting thekeyboard unit 7 and the circuit board 90 is fixed to the rear endportion of the lower surface of the keyboard substrate 87. Thus, theconnector 93 is situated in that position in the region between thekeyboard unit 7 and the PCB 63 where the distance between the twocomponents is greatest, so that the aforesaid region, which is liable tobe a dead space, can be effectively utilized. Further, a setting spacefor the connector 93 need not be secured over the circuit board in thebase unit 3, so that the degree of freedom of the circuit design can beimproved, and the apparatus can be made more compact.

As shown in FIGS. 3, 5 and 6, the computer is provided with a coolingmechanism 50 for cooling heating components in the housing. Themechanism 50 includes a cooling duct 52 which extends substantiallyacross the full width of the base unit 3 in the rear end portionthereof. The duct 52 contains capacitors 58, transformers 60, etc.,which constitute a driving power sources and radiate substantial heat.An intake end 52a of the duct 52 is closed, and a large number of intakeports 54 are formed in the end wall of the duct. Some of the ports 54face the intake ports 21 in the right-hand side wall of the top cover13, while the others open toward the keyboard unit 7. An exhaust end 52bof the duct 52 is open, and a cooling fan 97 is arranged facing theexhaust opening. The exhaust side of the fan 97 faces the exhaust ports23 in the left-hand side wall of the cover 13.

The fan 97 is fixed to the exhaust end 52b of the duct 52 by means of aplurality of screws 56. Spacers 66 are fixed between the duct 52 and thefan 97 by means of the screws 56, whereby the fan 97 is kept at apredetermined distance from the exhaust end of the duct.

As shown in FIGS. 6 and 7, a plurality of parallel guide ribs 62 areformed on the inner surface of the left-hand side wall of the top cover13 which faces the exhaust side of the cooling fan 97. The ribs 62,which extend substantially in the horizontal direction, are arranged atpredetermined intervals. Each rib 62 has a streamlined cross-sectionalshape. The exhaust ports 23 are formed between each two adjacent guideribs 62, and are arranged in the extending direction of the ribs. Guideribs 64, which resemble the guide ribs 62, are formed on the outersurface of the left-hand side wall of the top cover 13 so as to face theribs 62, individually.

As shown in FIG. 3, a large number of intake slits 103 are formed in afront end wall 101 of the bottom case 11 and arranged in the transversedirection of the base unit 3. Each slit 103 extends in parallel to thecircuit board 63. Cooling air is introduced into the unit 3 through theslits 103. Since the keyboard unit 7 is declined forward, as mentionedbefore, the front end wall 101 is lower than the other portions of thebase unit 3, and it is hard to form intake slits with a wide openingarea in the wall 101. Accordingly, the front end wall 101 is declinedforward with respect to the bottom wall of the bottom case 11. If theintake slits 103 are formed in the wall 101 inclined in this manner,their opening area can be made wider than in the case where the slitsare formed in a front end wall which extends at right angles to thebottom wall. Thus, the amount of intake air can be increased for highercooling efficiency.

Since the front end wall 101 is inclined, moreover, a recess 102 isdefined between the wall 101 and the grip section 59 of the handle 17.The recess 102 can be utilized as a finger recess which makes it easy todraw out the handle 17 from the base unit 3.

When the cooling fan 97 is actuated, in the cooling mechanism 50constructed in this manner, the outside air is introduced into the baseunit 3 through the intake ports 21 of the top cover 13. The introducedair flows into the cooling duct 52 through the intake ports 54 thereof,thereby cooling the heating parts 58, 60 in the duct, and is then guidedto the fan 97. Further, the air is discharged to the outside through theexhaust ports 23 of the top cover 13.

At the same time, the outside air is introduced into the base unit 3through the intake slits 103 in the front end wall 101 of the unit 3.After cooling the electronic parts on the main PCB 63, some of the airis guided to the cooling fan 97 through the intake ports 54 of thecooling duct 52 and the inside of the duct, and the remainder isdelivered directly to the fan. Thereafter, the introduced air isdischarged to the outside through the exhaust ports 23 by means of thefan 97.

In this manner, the heating components in the base unit 3 are cooled bymeans of the introduced outside air. The guide ribs 62 and 64 are formedalong the side edges of the exhaust ports 23, on the in- and outflowsides thereof, respectively. Each rib has a streamlined cross-sectionalshape. Therefore, the flow of the air discharged from the cooling fan 97can be regulated by means of the guide ribs 62 and 64 and smoothlyguided to the exhaust ports 23. Thus, the exhaust efficiency improved,so that the cooling efficiency inside the base unit 3 is improved. Asatisfactory effect can be obtained if the guide ribs are formed atleast on the inflow side of the exhaust ports 23, and the guide ribs 64on the outflow side may be omitted. Moreover, these guide ribs may beformed on the side of the .intake ports 21 as well as on the side of theexhaust ports 23. In this case, the intake efficiency can be improved.

As mentioned before, the cooling fan 97 is kept at the predetermineddistance from the exhaust end of the cooling duct 52 by means of thespacers 66. Therefore, eddies in the exhaust end portion 52b of the duct52 can be reduced, so that the intake efficiency of the fan 97 can beimproved, and the noise level of the fan can be lowered.

As shown in FIGS. 3 and 8, the bottom case 11 is formed having a storingsection 105 which is fitted with the expansion box 9. The section 105,which is located at the rear end portion of the case 11, is formed of asubstantially rectangular recess opening on the bottom surface, rearface, and right-hand side face of the case. This recess is defined by asubstantially horizontal bottom wall 105a, a vertically extending frontwall 105b, and a pair of side walls 105c. These walls are formedintegrally with the bottom cover 11. A pair of bosses 109 verticallyprotrude from the rear end portion of the bottom wall 105a. The extendedend of each boss 109 has a tapped hole 107 to mate with a screw forfixing the rear portion of the expansion box 9. The front wall 105b hasan opening 111 which opens into the base unit 3. The first connector 77attached to the main PCB 63 is exposed to the opening 111. A pair ofvertically extending guide projections 115 are formed on the front wall105b, on either side of the opening 111. Each projection 115 has a taperface 113 which serves to guide a connector (mentioned later) on the sideof the expansion box 9 to the first connector 77. A pair of engagingholes 135 are formed in the front wall 105b, on either side of theopening 111. Hooks of the expansion box 9 are fitted individually intothe holes 135 to fix the front end of the box 9 to the base unit 3.

The expansion box 9, which is removably fitted in the storing section105, is constructed as shown in FIG. 9.

The expansion box 9 is a rectangular structure which has open top andfront faces. The floppy disk drive (FDD) 117 is fixed to the centralportion of a bottom wall 9a of the box 9. A rectangular circuitsubstrate 121 is mounted on the front portion of the bottom wall 9a, andthe box-side connector 119, for use as a second connector, is fixed tothe substrate 121. The connector 119 is to be connected to the firstconnector 77 which is fixed to the main PCB 63. A pair of bosses 123protrude individually from the opposite end portions of the frontportion of the bottom wall 9a. Each boss 123 has a tapped hole used toscrew each end of the substrate 121. A pair of columnar projections 127protrude from the front portion of the bottom wall 9a so as to bealigned with their corresponding bosses 123. The distal end portion ofeach projection 127 is D-cut on the sides facing the opposite sideplates of the expansion box 9. Thus, the cross section of eachprojection 127 has the shape of a running track. The respective distalend portions of the projections 127 are fitted individually in a pair ofholes 125, which are bored through two corner portions of the substrate121 situated on a diagonal thereof. A pair of screws 131 are screwedindividually into the respective tapped holes of the bosses 123 throughholes 129, which are bored through the substrate 121. The screws 131used are threaded only partially. The diameter of each through hole 129is greater than that of the shank of each screw 131 and smaller thanthat of each boss 123. A leaf spring 133 is attached to the near centerof the front portion of the bottom wall 9a. The spring 133 electricallyconnects the substrate 121 and the expansion box 9 and urges thesubstrate 121 upward. A pair of engaging hooks 137 protrude forward fromthe front end of the wall 9a. These hooks 137 are fitted individually inthe engaging holes 135 in the front wall 105b of the storing section105, whereby the front end of the box 9 is fixed to the bottom case 11.

The engagement between the D-cut projections 127 and the holes 125 ofthe substrate 121 and the engagement between the screws 131 and thethrough holes 129, whose diameter is greater than that of the shank ofeach screw 131, prevent the circuit substrate 121 from moving in thelongitudinal direction of the box 9, that is, in the connectingdirection of the connectors 77 and 119, but allow the substrate 121 tomove for a predetermined distance in the transverse direction of thebox. Further, the engagement between the partially threaded screws 131and the holes 129 and the action of the leaf spring 133 allow thesubstrate 121 to move for a predetermined distance in the verticaldirection.

Accordingly, the box-side connector 119 fixed to the substrate 121 canmove for predetermined distances in the vertical and horizontaldirections with respect to the expansion box 9 or the first connector 77of the base unit 3. Thus, some dimensional error between the connector77 and the box-side connector 119 is permitted, and the connector 119can be securely connected to the connector 77 when the box 9 is fittedin the storing section 105. The box-side connector 119 can be disengagedfrom the connector 77 with a relatively small force, since the substrate121 has vertical and horizontal plays.

The substrate 121 is mounted with an upward connector 141 connected withan expansion board 139 for use as expanding means, an upward connector145 connected with a modem card 143, and an upward connector 147 forelectrically connecting the FDD 117 to the substrate 121. The board 139can be replaced with a new one at the operator's request. A second modemcard 149 is housed in the rear portion of the expansion box 9. The card149 is provided with an upward connector 151 for connecting the modemcard 143. Bosses 153 are provided at the rear end of the bottom wall 9aof the box 9. Each boss 153 has a hole through which a screw can befitted into the tapped hole 107 of each corresponding boss 109 of thestoring section 105. An exposure window 155 is formed on the rear wallof the expansion box 9. A connector (not shown) attached to the rear endof the expansion board 139 is exposed to the outside through the window155. Further, a cover 157 is rockably mounted on the rear face of thebox 9. When the window 155 is not in use, it is concealed by means ofthe cover 157.

If necessary, the operator can easily expand the function of thecomputer by removing the expansion box 9 from the storing section 105 ofthe base unit 3, connecting the expansion board 139, modem cards 143 and149, etc. to their corresponding connectors, and then mounting the box 9again in the storing section 105.

As shown in FIGS. 1 and 10, a latch mechanism 40, which includes thepair of latch hooks 39, is attached to the front end portion of thedisplay unit 5. The mechanism 40 is provided with latch holder 42 whichis fixed to the inside of the front end portion of the base frame 33 ofthe unit 5. The hooks 39 are rockably mounted on the holder 42.

As shown in FIGS. 10 to 13, each latch hook 39 includes a hook body 159,a pair of coil springs 161, a sliding projection 163, and a projectionholder 165. The hook body 159 is in the form of a substantiallyrectangular plate which has a hook portion 205 at its distal end. Arectangular recess 159a is formed in the inner surface of the body 159,and the sliding projection 163, substantially rectangular in shape, isfitted in the recess 159a for vertical sliding motion. The slidingmotion of the projection 163 is guided by means of a pair of guide ribs167 which protrude from the bottom surface of recess 159a. A pair ofbosses 169 also protrude from the bottom surface of the recess 159a.Each boss 169 has a tapped hole for a screw 162 used to fix theprojection holder 165. The torsion coil spring 161 surrounds each boss169. A pair of legs 171 protrude rearward from the lower end of the hookbody 159, and the respective projected end portions of the legs 171 areoutwardly bent in opposite directions. A pair of bosses 173 are formedindividually on the opposite side faces of the lower end portion of thehook body 159. The bosses 173 serve as pivot means for the latch hook 39which rotates relatively to the display unit 5. The bosses 173 arerotatably held by means of the latch holder 42.

The sliding projection 163 includes a substantially rectangular sliderplate 177 slidably fitted in the recess 159a of the hook body 159 and aprojection body 175 attached to the upper end of the plate 177 andextending perpendicular to the plate 177. The projection body 175 has apair of guide grooves 179 in which the guide ribs 167 are fittedindividually. The slider plate 177 is formed having a pair of firstslits 181, adapted to be guided by means of the bosses 169, and a pairof second slits 183 which allow the legs 171 to pass when the plate 177slides. One end of each coil spring 161 is anchored to its correspondingsecond slit 183. A tongue 185 protrudes rearward from the lower end ofthe sliding plate 177 and is situated between the second slits 183.

The projection holder 165 has a pair of third slits 187 and a pair ofholes 189 through which the screws 162 are inserted. When the slidingplate 177 slides, the one end of each coil spring 161 anchored to eachsecond slit 183 gets into its corresponding third slit 187.

When the hook body 159, coil springs 161, sliding projection 163, andprojection holder 165 are assembled together, as shown in FIG. 12, theprojection 163 is always subjected to an urging force in the directionof arrow A of FIG. 12 by means of the paired springs 161. When noexternal force is applied to the latch hook therefore, the slidingprojection 163 is held in the illustrated restricted position where theprojection body 175 abuts against the upper end face of the recess 159aof the hook body 159 to adjoin the hook portion 205.

As shown in FIGS. 10 and 13, the latch mechanism 40 includes an elongatecontrol plate 191 for use as an interlocking member which rocks inassociation with the latch hooks 39. The rocking motion of the hooks 39is allowed or prevented by the plate 191.

The opposite ends of the control plate 191, which individually face thelatch hooks 39, are supported individually by means of a pair ofsupporting portions 193 of the latch holder 42 for rocking motion. Apair of coil springs 195 are provided individually at the opposite endsof the control plate 191. These springs 195 urge the plate 191 in thedirection of arrow B of FIG. 13, that is, in the direction to recedefrom the latch hooks 39. Each of the opposite end portions of thecontrol plate 191 has a pair of U-shaped grooves 197 and a arm 199located between the grooves thereof. The grooves 197 extend in thelongitudinal direction and coaxial with one another. The legs 171 ofeach hook body 159 are rotatably fitted in their corresponding grooves197, and each arm 199 engages the tongue 185 of its correspondingsliding plate 177. The latch control plate 191 presses the latch hooks39 so that each hook rocks in the direction of arrow C of FIG. 13 aroundits corresponding bosses 173 by means of the urging force of the springs195. Each hook 39 engages a stopper (not shown) on the latch holder 42and held in the illustrated latch position. When no external force isapplied to the latch hooks 39, therefore, the plate 191 is kept in itsfirst position shown in FIG. 13.

FIG. 13 shows a state in which the display unit 5 is locked to itsclosed position by means of the latch mechanism 40. When the unit 5 isrocked to the closed position, each latch hook 39 engages itscorresponding latch hole 47 on the upper surface of the front end of thekeyboard unit 7. Thus, the hook body 159 and the sliding projection 163are kept in the latch position and the restricted position,respectively, while the control plate 191 is kept in the first position.In the latch position, the hook portion 205 of the hook body 159penetrates the latch hole 47 and engages the inner surface of thekeyboard frame 45. In the restricted position, the projection body 175of the sliding projection 163 is situated in the hole 47. The distance Jbetween the body 175 and the rear end edge of the hole 47 is shorterthan the length K of engagement between the hook portion 205 and theinner surface of the frame 45. If the latch hook 39 is slightlydisplaced in the direction of arrow D due to any causes, such asvibration, workmanship errors, etc., therefore, the projection body 175abuts against the rear end edge of the latch hole 47 before the hookportion 205 is disengaged from the keyboard frame 45, so that the hook39 is restrained from being further displaced. Thus, there is nopossibility of the latch hook 39 being unexpectedly disengaged from thelatch hole 47 to render the display unit 5 unlatched.

In releasing the latch mechanism 40 to unlatch the display unit 5, theoperator presses one or both of the latch hooks 39 in the direction ofarrow D of FIG. 13.

Thereupon, each latch hook 39 is rocked in the direction of arrow Earound its corresponding boss 173, as shown in FIG. 13. Then, thecontrol plate 191 is pressed by the legs 171 of the hook 39 in itsarcuate grooves 197 and rocked in the direction of arrow F of FIG. 14,resisting the urging force of the spring 195. As the plate 191 rocks inthis manner, the tongue 185 of the sliding projection 163 is pressed bythe arm 199 of the plate 191, so that the projection 163 is moved in thedirection of arrow G of FIG. 14. As a result, the projection body 175recedes from the latch hole 47, and the sliding projection 163 is movedto its retracted position shown in FIG. 14. Thus, the hook body 159 canbe rocked to its release position without any restrictions, and thecontrol plate 191 is rocked in interlock therewith to its secondposition, as shown in FIG. 14.

Even when only one of the latch hooks 39 is pressed in the direction ofarrow C, the resulting force of pressure is transmitted to the otherlatch hook through the control plate 191, so that the other hook alsoacts in the aforesaid manner.

By the operation described above, the latch hooks 39 are disengaged fromtheir corresponding latch holes 47, so that the display unit 5 isallowed to be swung open. If the press on the latch hook or hooks 39 isremoved after the unit 5 is opened, the hook bodies 159, the slidingprojections 163, and the control plate 191 are returned to the latchposition, the restricted position, and the first position, respectively,by the respective urging forces of the springs 161 and 195.

When the display unit 5 is rocked from the opened position to the closedposition, each latch hook 39 is automatically rocked in a manner suchthat the slope of its hook portion 205 is in contact with the edge ofthe latch hole 47, and is thus caused to engage the hole 47.

As shown in FIGS. 2 and 10, a dial key 55 is attached to the front endportion of the display unit 5. The key 55 is fixed to the latch holder42 and situated between the two latch hooks 39. As seen from FIG. 15,the key 55 has a lock arm 68, which is movable between a lockingposition and an unlocking position. In the locking position, asindicated by full line in FIG. 15, the arm 68 is in the path of transferof the control plate 191. In the unlocking position, as indicated bybroken line, the arm 68 is off the transfer path. When the key 55 is on,the lock arm 68 is held in the locking position, when the key 55 isturned off, the arm 68 is moved to the unlocking position.

The control plate 191 has a projection 192 which protrudes toward thelatch holder 42 from that region which faces the key 55. If the dial key55 is locked in a state such that each latch hook 39 is in engagementwith its corresponding latch hole 47, that is, each hook body 159 andthe control plate 191 are situated in the latch position and the firstposition, respectively, the lock arm 68 projects into the lockingposition, and engages the projection 192 of the plate 191. As a result,the control plate 191 is restrained from rocking in the direction ofarrow F of FIG. 14, and is locked to the first position as illustrated.As the rocking motion of the plate 191 is restrained in this manner, therocking of the hook body 159 is also restrained. Thus, the hook body 159is locked to the latch position in which it is in engagement with itscorresponding latch hole 47.

As the latch mechanism 40 is locked in this manner, the display unit 5is locked to the closed position. Even if each latch body 159 is bent tounlock the mechanism 40 by force, in this state, the projection body 175engages the rear end edge of its corresponding latch hole 47. Thus, thelatch mechanism 40 cannot be forcibly unlocked.

Since the computer itself can be disabled from operating when thedisplay unit 5 is prevented from being lifted from the base unit 3 byturning the key 55 on, wrong use of the apparatus can be securelyprevented.

It is to be understood that the present invention is not limited to theembodiment described above, and that various changes and modificationsmay be effected therein by one skilled in the art without departing fromthe scope or spirit of the invention.

For example, the key is not limited to the aforementioned combinationlock, and may be of any type which is provided with a lock membercapable of projecting into the path of transfer of the control plate.

What is claimed is:
 1. A portable electronic apparatus comprising:ahousing having a bottom wall carrying a circuit board thereon; asubstantially rectangular keyboard unit mounted on the housing andfacing the circuit board, a peripheral edge portion of the keyboard unitbeing supported on the housing; a shielding plate arranged adjacent tothe keyboard unit between the circuit board and the keyboard unit, formagnetically shielding the circuit board; and means for preventing thekeyboard unit from bending toward the circuit board, the preventingmeans including a supporting member extending from the shielding plateand having an extended end abutting against the circuit board.
 2. Anapparatus according to claim 1, wherein said shielding plate is asubstantially rectangular structure having substantially the same sizeas the keyboard unit, and said preventing means includes a plurality ofsaid supporting members extending from substantially the central portionof the shielding plate.
 3. An apparatus according to claim 2, whereinsaid housing has a plurality of bosses protruding from the bottom wall,said circuit board is placed on the bosses, and said supporting membersare aligned with the bosses.
 4. An apparatus according to claim 3,wherein said preventing means includes a plurality of cushioning membersdisposed between the extended ends of the supporting members and thecircuit board.
 5. An apparatus according to claim 4, wherein saidpreventing means includes a plurality of another cushioning membersdisposed between the keyboard unit and the shielding plate, the anothercushioning members being aligned with the supporting members.
 6. Aportable electronic apparatus comprising:a housing having a bottom wall;a circuit board proximate to the bottom wall; a keyboard unit mounted onthe housing and facing the circuit board; a shielding plate disposedbetween the circuit board and the keyboard unit for magneticallyshielding the circuit board; and spacing means, disposed between thecircuit board and the shielding plate, for maintaining spacing betweenthe circuit board and the shielding plate.
 7. A portable electronicapparatus according to claim 6, wherein the keyboard unit includes aperipheral edge portion supported on the housing, and the shieldingplate includes an edge portion, the edge portion of the shielding plateincluding a supported portion, the supported portion being supported onthe housing.
 8. A portable electronic apparatus according to claim 6,wherein the spacing means has an end face, the circuit board has anupper portion, and wherein the portable electronic apparatus furthercomprises:a plurality of cushioning members disposed in the upperportion of the circuit board facing the end face of the spacing means.9. A portable electronic apparatus comprising:a housing having at leastone boss on a bottom wall thereof; a circuit board mounted on the atleast one boss; a keyboard unit mounted on the housing and facing thecircuit board, the keyboard unit having a peripheral edge portion, theperipheral edge portion of the keyboard unit being supported on thehousing; a shielding plate disposed between the circuit board and thekeyboard unit for magnetically shielding the circuit board; and spacingmeans, disposed between the circuit board and the shielding plate, formaintaining spacing between the circuit board and the shielding plate.10. A portable electronic apparatus according to claim 9, wherein theshielding plate has a supported portion in an edge portion of theshielding plate, the supported portion being supported on the housing.11. A portable electronic apparatus according to claim 9, wherein thespacing means has an end face, the circuit board has an upper portion,and wherein the portable electronic apparatus further comprises:at leastone cushioning member disposed in the upper portion of the circuit boardfacing the end face of the spacing means.
 12. A portable electronicapparatus according to claim 11, wherein said at least one boss and acorresponding cushioning member are arranged in a line substantiallyperpendicular to the bottom wall.
 13. A portable electronic apparatuscomprising:a housing having a bottom wall; a circuit board proximate tothe bottom wall; a shielding plate disposed proximate to the circuitboard, the shielding plate having an edge portion supported on thehousing for magnetically shielding the circuit board; at least onespacing means, disposed between the circuit board and the shieldingplate, for maintaining spacing between the circuit board and theshielding plate; and at least one boss disposed between the bottom walland the circuit board.
 14. A portable electronic apparatus according toclaim 13, further comprising a keyboard unit mounted on the shieldingplate, the shielding plate having a supported portion supported on thehousing.
 15. A portable electronic apparatus according to claim 13,further comprising at least one cushioning member disposed between thecircuit board and the spacing means.
 16. A portable electronic apparatusaccording to claim 15, wherein said at least one spacing means, acorresponding boss, and a corresponding cushioning member are arrangedin a line substantially perpendicular to the bottom wall.
 17. A portableelectronic apparatus comprising:a housing having a bottom wall; acircuit board proximate to the bottom wall; a shielding plate disposedproximate to the circuit board for magnetically shielding the circuitboard, the shielding plate having an edge portion being supported on thehousing; a plurality of bosses disposed between the bottom wall and thecircuit board; and means for preventing the shielding plate from bendingtoward the circuit board, the preventing means including a supportingmember which extends from the shielding plate and has an extended endabutting against the circuit board.
 18. A portable electronic apparatusaccording to claim 17, further comprising a keyboard unit mounted on theshielding plate, the shielding plate having a supported portionsupported on the housing.
 19. A portable electronic apparatus accordingto claim 17, further comprising a plurality of cushioning membersdisposed between the circuit board and the preventing means.
 20. Aportable electronic apparatus according to claim 19, wherein thepreventing means, a corresponding boss, and a corresponding cushioningmember are arranged in a line substantially perpendicular to the bottomwall.